Model 3 Regeneration vs. Temperature & Accessory Consumption

[pigwet]

Exploring the data available from Scan My Tesla.

First is getting a better understanding of regeneration power vs. battery temperature. First plot shows two datasets on different days. I have yet to find my battery temperature below ~49F despite it being much colder outside. We'll see if I can expand this graph as there's still some solid line left below the drive mode indicator (2/3rd dots). 75kW is a lot of power considering typical steady state charge levels at home! It's not uncommon for me to regenerate 1/3rd of the total power consumption on a typical city drive: final battery consumption 10kWh, regen 5kWh, total consumption 15kWh (calculated value) .

Second graph is power consumption with the heater turned on full blast, no other accessories on. I've noticed different peak power draw depending on if the car is on (ACC on) vs. being turned on with the App, etc. This graph represents what I've seen as the highest power draw I've recorded which is when I turn the heat on with the App and don't actually enter the car.

More charts coming for lights, wipers, etc. at some point.

 

[pigwet]

Adding/updating second plot to include battery temperature. Read that pre-heating from the app heats the battery and the cabin. Now I'm interested to verify lower battery consumption if pre-heating by setting the cabin temperature manually vs. via the app. More to come.

 

[pigwet]

Very different consumption profile when setting the heat to MAX inside the car, and setting the climate control to remain on after exiting the vehicle. Similar ambient temperatures outside of vehicle, ~40F in garage. Car sat all night to let battery cool and once again remained around 50F.

 

[AlanSubie4Life]

Very different consumption profile when setting the heat to MAX inside the car, and setting the climate control to remain on after exiting the vehicle. Similar ambient temperatures outside of vehicle, ~40F in garage. Car sat all night to let battery cool and once again remained around 50F. View attachment 503462

Thanks for all this data. Very nice.

Are these done with the car plugged in, I assume? <EDIT: I see in your plot titles they are all unplugged...interesting>. Can you verify what happens when the car is plugged in (the expectation is the battery will not preheat in that case)?

For this unplugged case, what was the SoC? Can you see if the behavior changes below 70% SoC? There is some thinking going around that the battery heating behavior may depend on the state of charge, or perhaps more importantly, the amount of regen limiting currently in force. So I guess the question is: with no regen limitations in the car, but with a cold battery, do you find that the stator heating is disabled and battery temp stays fairly steady, except for incidental heating from the cabin (that would make sense...)

Is your car RWD? It looks like only one stator heater is being engaged (3.5kW + 9kW).

For the heat on MAX, is the AC on or off? For all the plots? These numbers seem consistent with AC on (7kW heat + 2kW AC).

In the last plot, where you left climate on, was the car already up to the correct temperature inside? <Edit: sounds like it had been sitting....> Thoughts on why you did not see the oscillating power draw?

What are the blue dots in the first plot?

 

[ElectricIAC]

Exploring the data available from Scan My Tesla.

First is getting a better understanding of regeneration power vs. battery temperature. First plot shows two datasets on different days. I have yet to find my battery temperature below ~49F despite it being much colder outside. We'll see if I can expand this graph as there's still some solid line left below the drive mode indicator (2/3rd dots). 75kW is a lot of power considering typical steady state charge levels at home! It's not uncommon for me to regenerate 1/3rd of the total power consumption on a typical city drive: final battery consumption 10kWh, regen 5kWh, total consumption 15kWh (calculated value) .

Second graph is power consumption with the heater turned on full blast, no other accessories on. I've noticed different peak power draw depending on if the car is on (ACC on) vs. being turned on with the App, etc. This graph represents what I've seen as the highest power draw I've recorded which is when I turn the heat on with the App and don't actually enter the car.

More charts coming for lights, wipers, etc. at some point.

View attachment 502817 View attachment 502818

Looks interesting..

 

[pigwet]

0. All cabin heating done unplugged so far.
1. Blue dots in first graph are regen data from a different day. Lines up nicely.
2. Car is AWD.
3. AC is on in all heating graphs.
4. Starting inside car temperature was similar on both days - in the 40's.
5. Oscillations on App only heating: not sure why. Will explore if always that way.
6. State of charge: The app approach with oscillations started at 80% SOC in the morning. The second non-app approach started at 68% and went down to 62%.

To do:
0. Graph 5 below adds stator temps to 4th graph.
1. Repeat when plugged in, yes in a few days.
2. Not sure how to get a cold battery with warm stators. Perhaps just normal easy driving accomplishes that.

 

[AlanSubie4Life]

If you do a 3D plot of regen peak (z) (max of regen) vs. temperature (x) and battery SoC (y) that might be an interesting looking surface to look at. Might be hard to see but maybe not.

For regen, what is hard to capture is the memory effect of regen - seems that separate of temperature and SoC there is a history of recent regen that can kick in - can’t do too much all at once. Presumably the cloud of lithium gets too dense due to limited rate of migration and starts to plate at some point. Or something.

The stator heating when unplugged and not especially cold is surprising (I would have thought it would be a waste of energy at least at low SoC). Do you think this is a function of setting the heat to “max”? If you had say, 70 degrees set, does it happen (and does it depend on SoC in that lower temp case)? Did you hit the defrost button in the app?

 

[taraquin]

According to Teslabjørn stators are rarely active when preheating except when navigating to SC. It seem like stators preheat battery, but remain inactive while driving. Smart behaviour which gives a low powercobsumption while actually driving.

 

[GtiMart]

The current active heating temperature setting is 10C (50F) so any battery temp below that and the car will heat the battery when you preheat the car. That's what I'm observing here.

 

[taraquin]

The current active heating temperature setting is 10C (50F) so any battery temp below that and the car will heat the battery when you preheat the car. That's what I'm observing here.

what happends when driving if temp target is not achieves during preheat? Does it actively heat battery while driving aswell with stators? Or just passive?

 

[GtiMart]

I see it only continuing to circulate the heating/cooling liquid and drawing whatever heat there is in the motors/stators. I don't see energy consumption in the motors purely for the sake of heating. Now sometimes i have seen one engine regen when slowing down while the other engine does a bit of work to pull the car, but less than regen. Maybe that is to generate a bit of heat...

 

[GtiMart]

I forgot to say in my last comment that when the car does that (regen and produce forward force at the same time) it's because the battery is too cold to take all that regen charge. It's almost free energy to heat the other engine. Tesla engineers have many good ideas!

 

[AlanSubie4Life]

Something for @pigwet to add to the list of experiments - try some of these things with the car sitting in drive.

 

[taraquin]

I forgot to say in my last comment that when the car does that (regen and produce forward force at the same time) it's because the battery is too cold to take all that regen charge. It's almost free energy to heat the other engine. Tesla engineers have many good ideas!

I wrote a post about that a couple of months ago. That when the car dont have enough regen due to low temp the motor could generate waste heat, 7kW in the Model 3, which especially in long down hills can conyribute quite a bit. Really cool if Tesla actually has implemented that in TM3

 

[pigwet]

More data, now with the car plugged in wtih 14-30 adapter. SOC was 79-80%.

First is max heat turned on via the APP, day 1.
Second is a continuation of day 1 after max heat turned on via APP, followed by "Keep Climate on".
Third is max heat turned on by "Keep Climate On", day 2.

Overall, the battery warms up while plugged in, albeit more slowly than when unplugged.

Some interesting behavior with the stators again. (For some reason the data is not populating when the stator temp doesn't change temperature hence the lack of continuous curves, or lack of curves entirely in 2nd graph)

I happened to be standing near the car during the "Climate On" run around 17 minutes and you could hear fans kick in and saw the stator temp shoot up.

 

[cstork]

Can someone answer these questions:
1) If the car and battery are at 20F (-7C), how many KWh are used to bring the car and battery up to 70F (21C) ? I assume this doesn't make a difference whether driving or pre-heating.
2) How long does it take for the battery to heat up from 20F to 70F when doing preheat not plugged in?
Thank you.

 

[taraquin]

I forgot to say in my last comment that when the car does that (regen and produce forward force at the same time) it's because the battery is too cold to take all that regen charge. It's almost free energy to heat the other engine. Tesla engineers have many good ideas!

I wonder how this works on cars with single motors?

 

[rrolsbe]

I wrote a post about that a couple of months ago. That when the car dont have enough regen due to low temp the motor could generate waste heat, 7kW in the Model 3, which especially in long down hills can conyribute quite a bit. Really cool if Tesla actually has implemented that in TM3

Interesting thread. It would seem reasonable to heat the motor stator(s) with at least part of the regen power to help warm a traction battery that is to cold to accept the full regen the motor(s) are capable of delivering. The portion of the regen power delivered to the stator would not help slow the car but would, at the very least, help keep the battery from becoming even colder when no or very little forward motion power is required (like going down a long grade). If the car does not have full regen, sending some regen power to the stator should help warm the traction battery quicker which would also increase regen. Maybe Tesla is already doing this? The SMT app could prove what Tesla has or has not implemented.

 

[rrolsbe]

After further thinking regarding my previous post, I wonder whether SMT does or could display what portion of the stator power is being supplied from the traction battery (for forward motion) or from the regen function? Tesla displays green on the power bar when power is being sent back into the traction battery and black when power is outbound from the traction battery to the motor(s). I normally only see reduced regen but I think the traction battery is not capable of accepting ANY regen when the traction battery nears 32F. If true, the motor stator windings could potentially sync up to 8KW from regen (for the soul purpose of creating heat) when power is not required for forward motion. Simply coasting and not using any regen, when the traction battery is very cold, strikes me as not the optimal engineering solution. It is also possible that power from the regen function can never be sent directly to the stator windings?

 

[taraquin]

It would not surprice me if Tesla found a way to send regen steaight to stators, this would also aid braking as energy is being recovered. I hope they actually do this

One thing that puzzles me is that li-ion batteries can charge/regen below 0C without lithoum plating, but you have to charge slow/allow for low regen. Typically only a few kW, but combined with energy put straight to stators this could eadily result in 10-15kW of energy recovered and additional heating of the system.

Does anyone kniw how much the stators in RWD-motor generates while preheating battery? In AWD it is about 7kW, but I wonder how much it is with only one motor.